Ultrafast Quantum-Well Photodetectors Operating at 10 μm with a Flat Frequency Response up to 70 GHz at Room Temperature

Abstract

III-V semiconductor mid-infrared photodetectors based on intersubband transitions hold a great potential for ultra-high-speed operation up to several hundreds of GHz. In this work we exploit a ~350nm-thick GaAs/Al0.2Ga0.8As multi-quantum-well heterostructure to demonstrate heterodyne detection at l~10µm with a nearly flat frequency response up to 70GHz at room temperature, solely limited by the measurement system bandwidth. This is the broadest RFbandwidth reported to date for a quantum-well mid-infrared photodetector. Responsivities of 0.15A/W and 1.5A/W are obtained at 300K and 77K respectively. To allow ultrafast operation and illumination at normal incidence, the detector consists of a 50W coplanar waveguide, monolithically integrated with a 2D-array of sub-wavelength patch antennas, electrically interconnected by suspended wires. With this device architecture we obtain a parasitic capacitance of ~30fF, corresponding to the static capacitance of the antennas, yielding a RClimited 3dB cutoff frequency >150GHz at 300K, extracted with a small-signal equivalent circuit model. Using this model, we quantitively reproduce the detector frequency response and find intrinsic roll-off time constants as low as 1ps at room temperature.

Mid-infrared free-space cryptosystem

“…The quantum cascade laser (QCL) technology has known tremendous improvements in the past two decades, boosted by the need for mid-infrared frequency combs for precision spectroscopy [1] and highpower low-divergence beams [2] for military applications. There is nowadays a growing interest for high-speed devices relying on quantum well and quantum cascade structures either on the emission side [3] or on the reception side [4,5], even if QCLs for free-space communication has long been envisioned [6]. The main advantage of mid-infrared wavelength is that it is less affected by atmospheric conditions than near-infrared wavelength, thus the superiority of mid-infrared light for long-range freespace transmission [7].…”

Гетероструктура Квантово-Каскадного Детектора Частотного Диапазона 2.5 ТГц

“…Несмотря на наличие быстродействующих детекторов ближнего [7] и среднего [8] инфракрасного (ИК) диапазонов, отсутствие быстродействующих детекторов дальнего ИК (ТГц диапазона), способных обеспечить интеграцию на чипе, существенно ограничивает развитие компактных систем двойной гребенчатой спектроскопии.…”

“…Однако существуют физические ограничения на работу ТГц QWIP при комнатной температуре. Более того, быстродействующие QWIP (частота отсечки на уровне 70 ГГц) были продемонстрированы на длинах волн ∼ 10 мкм [8]. В то же время быстродействие ТГц QWIP не превышает 4.3 ГГц [10,11].…”

Methodology of optimisation for a nanostructured two-photon absorption photodetector

“…and to locally enhance the electrical field [18]. In the case of infrared photodetection, these properties have proven to enhance sensing performances [19,20,21], mainly thanks to the reduction of the absorbing semiconductor volume. As well, the low efficiency of two-photon absorption can be improved thanks to the concentration ability of nanostructures [12] -even in the challenging case of bi-spectral optimisation.…”